This application claims priority from Korean Patent Application No. 10-2004-0022888, filed on Apr. 2, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a method for preparing lysine granules used as an animal feed additive and lysine granules prepared by the method.
2. Description of the Related Art
U.S. Pat. No. 5,431,933 discloses an animal feed additive containing most of components of a fermentation broth and a method for preparing the same. According to the method disclosed in this patent, a slightly hygroscopic and sticky animal feed additive with an amino acid content of 40 to 90% can be prepared at a low cost. However, the animal feed additive has disadvantages such as a low density and a large variation in component contents. That is, the content of a lysine in the fermentation broth varies according to a fermentation condition, which in turn causes a variation in the content of a lysine contained in the animal feed additive based on the fermentation broth.
U.S. Pat. No. 5,622,710 discloses a method for preparing animal feed additive pellets, which includes: directly spray-drying a fermentation broth containing an assimilable sugar of 0.3% or less to obtain fine granules and mixing the fine granules with a binder such as water and a fermentation broth. The animal feed additive pellets prepared according to this method disclosed in this patent have a density of 550 kg/m3 or more, an amino acid content of 40 to 90%, and low hygroscopic property and stickiness. However, the formation of the fine granules from the fermentation broth and the mixing of the fine granules with the fermentation broth by an intensive mixer increase a process complexity.
U.S. Pat. No. 5,133,976 discloses a method for preparing an animal feed additive containing a lysine content of 35 to 48%, which includes: culturing a lysine producing microorganism while maintaining an assimilable sugar of 5 to 15 g/l; concentrating the resultant culture to obtain a concentrate with a solid content of 50 to 75%; and dehydrating the concentrate by azeotropic distillation. However, there are disadvantages in that a lysine content is low, the azeotropic distillation increases a process cost and a process complexity, and the animal feed additive is easily made into fine powders.
As described above, conventional animal feed additives containing lysine have a problem in that the contents of components of the animal feed additives are largely changed depending on various parameters of a fermentation process. Therefore, the present inventors found a method for preparing a lysine-containing animal feed additive based on a fermentation broth which has the standardized content of a lysine and excellent nutritive properties even though component contents change depending on fermentation conditions and completed the present invention.